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1206 lines
48 KiB
C++
1206 lines
48 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <cassert>
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#include <iostream>
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#include <iomanip>
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#include <sstream>
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#include <algorithm>
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#include "bitcount.h"
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#include "evaluate.h"
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#include "material.h"
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#include "pawns.h"
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#include "thread.h"
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#include "ucioption.h"
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namespace {
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// Struct EvalInfo contains various information computed and collected
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// by the evaluation functions.
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struct EvalInfo {
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// Pointers to material and pawn hash table entries
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MaterialInfo* mi;
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PawnInfo* pi;
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// attackedBy[color][piece type] is a bitboard representing all squares
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// attacked by a given color and piece type, attackedBy[color][0] contains
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// all squares attacked by the given color.
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Bitboard attackedBy[2][8];
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// kingRing[color] is the zone around the king which is considered
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// by the king safety evaluation. This consists of the squares directly
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// adjacent to the king, and the three (or two, for a king on an edge file)
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// squares two ranks in front of the king. For instance, if black's king
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// is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
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// f7, g7, h7, f6, g6 and h6.
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Bitboard kingRing[2];
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// kingAttackersCount[color] is the number of pieces of the given color
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// which attack a square in the kingRing of the enemy king.
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int kingAttackersCount[2];
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// kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
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// given color which attack a square in the kingRing of the enemy king. The
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// weights of the individual piece types are given by the variables
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// QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
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// KnightAttackWeight in evaluate.cpp
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int kingAttackersWeight[2];
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// kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
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// directly adjacent to the king of the given color. Pieces which attack
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// more than one square are counted multiple times. For instance, if black's
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// king is on g8 and there's a white knight on g5, this knight adds
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// 2 to kingAdjacentZoneAttacksCount[BLACK].
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int kingAdjacentZoneAttacksCount[2];
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};
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// Evaluation grain size, must be a power of 2
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const int GrainSize = 8;
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// Evaluation weights, initialized from UCI options
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enum { Mobility, PassedPawns, Space, KingDangerUs, KingDangerThem };
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Score Weights[6];
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typedef Value V;
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#define S(mg, eg) make_score(mg, eg)
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// Internal evaluation weights. These are applied on top of the evaluation
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// weights read from UCI parameters. The purpose is to be able to change
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// the evaluation weights while keeping the default values of the UCI
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// parameters at 100, which looks prettier.
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//
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// Values modified by Joona Kiiski
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const Score WeightsInternal[] = {
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S(252, 344), S(216, 266), S(46, 0), S(247, 0), S(259, 0)
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};
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// MobilityBonus[PieceType][attacked] contains mobility bonuses for middle and
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// end game, indexed by piece type and number of attacked squares not occupied
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// by friendly pieces.
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const Score MobilityBonus[][32] = {
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{}, {},
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{ S(-38,-33), S(-25,-23), S(-12,-13), S( 0, -3), S(12, 7), S(25, 17), // Knights
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S( 31, 22), S( 38, 27), S( 38, 27) },
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{ S(-25,-30), S(-11,-16), S( 3, -2), S(17, 12), S(31, 26), S(45, 40), // Bishops
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S( 57, 52), S( 65, 60), S( 71, 65), S(74, 69), S(76, 71), S(78, 73),
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S( 79, 74), S( 80, 75), S( 81, 76), S(81, 76) },
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{ S(-20,-36), S(-14,-19), S( -8, -3), S(-2, 13), S( 4, 29), S(10, 46), // Rooks
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S( 14, 62), S( 19, 79), S( 23, 95), S(26,106), S(27,111), S(28,114),
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S( 29,116), S( 30,117), S( 31,118), S(32,118) },
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{ S(-10,-18), S( -8,-13), S( -6, -7), S(-3, -2), S(-1, 3), S( 1, 8), // Queens
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S( 3, 13), S( 5, 19), S( 8, 23), S(10, 27), S(12, 32), S(15, 34),
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S( 16, 35), S( 17, 35), S( 18, 35), S(20, 35), S(20, 35), S(20, 35),
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S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
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S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
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S( 20, 35), S( 20, 35) }
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};
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// OutpostBonus[PieceType][Square] contains outpost bonuses of knights and
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// bishops, indexed by piece type and square (from white's point of view).
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const Value OutpostBonus[][64] = {
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{
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// A B C D E F G H
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
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V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
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V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
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V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
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V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },
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{
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
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V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
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V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
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V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
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V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
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V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }
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};
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// ThreatBonus[attacking][attacked] contains threat bonuses according to
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// which piece type attacks which one.
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const Score ThreatBonus[][8] = {
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{}, {},
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{ S(0, 0), S( 7, 39), S( 0, 0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT
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{ S(0, 0), S( 7, 39), S(24, 49), S( 0, 0), S(41,100), S(41,100) }, // BISHOP
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{ S(0, 0), S(-1, 29), S(15, 49), S(15, 49), S( 0, 0), S(24, 49) }, // ROOK
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{ S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0, 0) } // QUEEN
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};
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// ThreatenedByPawnPenalty[PieceType] contains a penalty according to which
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// piece type is attacked by an enemy pawn.
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const Score ThreatenedByPawnPenalty[] = {
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S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
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};
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#undef S
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// Rooks and queens on the 7th rank (modified by Joona Kiiski)
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const Score RookOn7thBonus = make_score(47, 98);
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const Score QueenOn7thBonus = make_score(27, 54);
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// Rooks on open files (modified by Joona Kiiski)
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const Score RookOpenFileBonus = make_score(43, 43);
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const Score RookHalfOpenFileBonus = make_score(19, 19);
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// Penalty for rooks trapped inside a friendly king which has lost the
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// right to castle.
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const Value TrappedRookPenalty = Value(180);
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// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
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// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
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// happen in Chess960 games.
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const Score TrappedBishopA1H1Penalty = make_score(100, 100);
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// The SpaceMask[Color] contains the area of the board which is considered
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// by the space evaluation. In the middle game, each side is given a bonus
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// based on how many squares inside this area are safe and available for
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// friendly minor pieces.
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const Bitboard SpaceMask[] = {
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(1ULL << SQ_C2) | (1ULL << SQ_D2) | (1ULL << SQ_E2) | (1ULL << SQ_F2) |
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(1ULL << SQ_C3) | (1ULL << SQ_D3) | (1ULL << SQ_E3) | (1ULL << SQ_F3) |
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(1ULL << SQ_C4) | (1ULL << SQ_D4) | (1ULL << SQ_E4) | (1ULL << SQ_F4),
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(1ULL << SQ_C7) | (1ULL << SQ_D7) | (1ULL << SQ_E7) | (1ULL << SQ_F7) |
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(1ULL << SQ_C6) | (1ULL << SQ_D6) | (1ULL << SQ_E6) | (1ULL << SQ_F6) |
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(1ULL << SQ_C5) | (1ULL << SQ_D5) | (1ULL << SQ_E5) | (1ULL << SQ_F5)
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};
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// King danger constants and variables. The king danger scores are taken
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// from the KingDangerTable[]. Various little "meta-bonuses" measuring
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// the strength of the enemy attack are added up into an integer, which
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// is used as an index to KingDangerTable[].
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//
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// KingAttackWeights[PieceType] contains king attack weights by piece type
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const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
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// Bonuses for enemy's safe checks
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const int QueenContactCheckBonus = 6;
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const int RookContactCheckBonus = 4;
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const int QueenCheckBonus = 3;
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const int RookCheckBonus = 2;
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const int BishopCheckBonus = 1;
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const int KnightCheckBonus = 1;
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// InitKingDanger[Square] contains penalties based on the position of the
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// defending king, indexed by king's square (from white's point of view).
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const int InitKingDanger[] = {
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2, 0, 2, 5, 5, 2, 0, 2,
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2, 2, 4, 8, 8, 4, 2, 2,
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7, 10, 12, 12, 12, 12, 10, 7,
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15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15
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};
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// KingDangerTable[Color][attackUnits] contains the actual king danger
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// weighted scores, indexed by color and by a calculated integer number.
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Score KingDangerTable[2][128];
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// TracedTerms[Color][PieceType || TracedType] contains a breakdown of the
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// evaluation terms, used when tracing.
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Score TracedScores[2][16];
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std::stringstream TraceStream;
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enum TracedType {
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PST = 8, IMBALANCE = 9, MOBILITY = 10, THREAT = 11,
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PASSED = 12, UNSTOPPABLE = 13, SPACE = 14, TOTAL = 15
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};
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// Function prototypes
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template<bool Trace>
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Value do_evaluate(const Position& pos, Value& margin);
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template<Color Us>
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void init_eval_info(const Position& pos, EvalInfo& ei);
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template<Color Us, bool Trace>
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Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility);
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template<Color Us, bool Trace>
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Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]);
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template<Color Us>
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Score evaluate_threats(const Position& pos, EvalInfo& ei);
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template<Color Us>
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int evaluate_space(const Position& pos, EvalInfo& ei);
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template<Color Us>
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Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
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Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei);
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inline Score apply_weight(Score v, Score weight);
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Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf);
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Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
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void init_safety();
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double to_cp(Value v);
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void trace_add(int idx, Score term_w, Score term_b = SCORE_ZERO);
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}
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/// evaluate() is the main evaluation function. It always computes two
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/// values, an endgame score and a middle game score, and interpolates
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/// between them based on the remaining material.
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Value evaluate(const Position& pos, Value& margin) { return do_evaluate<false>(pos, margin); }
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namespace {
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template<bool Trace>
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Value do_evaluate(const Position& pos, Value& margin) {
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EvalInfo ei;
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Value margins[2];
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Score score, mobilityWhite, mobilityBlack;
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assert(pos.thread() >= 0 && pos.thread() < MAX_THREADS);
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assert(!pos.in_check());
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// Initialize score by reading the incrementally updated scores included
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// in the position object (material + piece square tables).
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score = pos.value();
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// margins[] store the uncertainty estimation of position's evaluation
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// that typically is used by the search for pruning decisions.
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margins[WHITE] = margins[BLACK] = VALUE_ZERO;
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// Probe the material hash table
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ei.mi = Threads[pos.thread()].materialTable.material_info(pos);
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score += ei.mi->material_value();
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// If we have a specialized evaluation function for the current material
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// configuration, call it and return.
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if (ei.mi->specialized_eval_exists())
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{
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margin = VALUE_ZERO;
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return ei.mi->evaluate(pos);
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}
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// Probe the pawn hash table
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ei.pi = Threads[pos.thread()].pawnTable.pawn_info(pos);
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score += ei.pi->pawns_value();
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// Initialize attack and king safety bitboards
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init_eval_info<WHITE>(pos, ei);
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init_eval_info<BLACK>(pos, ei);
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// Evaluate pieces and mobility
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score += evaluate_pieces_of_color<WHITE, Trace>(pos, ei, mobilityWhite)
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- evaluate_pieces_of_color<BLACK, Trace>(pos, ei, mobilityBlack);
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score += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
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// Evaluate kings after all other pieces because we need complete attack
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// information when computing the king safety evaluation.
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score += evaluate_king<WHITE, Trace>(pos, ei, margins)
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- evaluate_king<BLACK, Trace>(pos, ei, margins);
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// Evaluate tactical threats, we need full attack information including king
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score += evaluate_threats<WHITE>(pos, ei)
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- evaluate_threats<BLACK>(pos, ei);
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// Evaluate passed pawns, we need full attack information including king
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score += evaluate_passed_pawns<WHITE>(pos, ei)
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- evaluate_passed_pawns<BLACK>(pos, ei);
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// If one side has only a king, check whether exists any unstoppable passed pawn
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if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
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score += evaluate_unstoppable_pawns(pos, ei);
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// Evaluate space for both sides, only in middle-game.
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if (ei.mi->space_weight())
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{
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int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
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score += apply_weight(make_score(s * ei.mi->space_weight(), 0), Weights[Space]);
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}
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// Scale winning side if position is more drawish that what it appears
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ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
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: ei.mi->scale_factor(pos, BLACK);
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// If we don't already have an unusual scale factor, check for opposite
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// colored bishop endgames, and use a lower scale for those.
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if ( ei.mi->game_phase() < PHASE_MIDGAME
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&& pos.opposite_colored_bishops()
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&& sf == SCALE_FACTOR_NORMAL)
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{
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// Only the two bishops ?
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if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
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&& pos.non_pawn_material(BLACK) == BishopValueMidgame)
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{
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// Check for KBP vs KB with only a single pawn that is almost
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// certainly a draw or at least two pawns.
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bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
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sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
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}
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else
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// Endgame with opposite-colored bishops, but also other pieces. Still
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// a bit drawish, but not as drawish as with only the two bishops.
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sf = ScaleFactor(50);
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}
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// Interpolate between the middle game and the endgame score
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margin = margins[pos.side_to_move()];
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Value v = scale_by_game_phase(score, ei.mi->game_phase(), sf);
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// In case of tracing add all single evaluation contributions for both white and black
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if (Trace)
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{
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trace_add(PST, pos.value());
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trace_add(IMBALANCE, ei.mi->material_value());
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trace_add(PAWN, ei.pi->pawns_value());
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trace_add(MOBILITY, apply_weight(mobilityWhite, Weights[Mobility]), apply_weight(mobilityBlack, Weights[Mobility]));
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trace_add(THREAT, evaluate_threats<WHITE>(pos, ei), evaluate_threats<BLACK>(pos, ei));
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trace_add(PASSED, evaluate_passed_pawns<WHITE>(pos, ei), evaluate_passed_pawns<BLACK>(pos, ei));
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trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei));
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Score w = make_score(ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei), 0);
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Score b = make_score(ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei), 0);
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trace_add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
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trace_add(TOTAL, score);
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TraceStream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
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<< ", Black: " << to_cp(margins[BLACK])
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<< "\nScaling: " << std::noshowpos
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<< std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
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<< std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
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<< std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
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<< "Total evaluation: " << to_cp(v);
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}
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return pos.side_to_move() == WHITE ? v : -v;
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}
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} // namespace
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/// read_weights() reads evaluation weights from the corresponding UCI parameters
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void read_evaluation_uci_options(Color us) {
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// King safety is asymmetrical. Our king danger level is weighted by
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// "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
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const int kingDangerUs = (us == WHITE ? KingDangerUs : KingDangerThem);
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|
const int kingDangerThem = (us == WHITE ? KingDangerThem : KingDangerUs);
|
|
|
|
Weights[Mobility] = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
|
|
Weights[PassedPawns] = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
|
|
Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
|
|
Weights[kingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
|
|
Weights[kingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
|
|
|
|
// If running in analysis mode, make sure we use symmetrical king safety. We do this
|
|
// by replacing both Weights[kingDangerUs] and Weights[kingDangerThem] by their average.
|
|
if (Options["UCI_AnalyseMode"])
|
|
Weights[kingDangerUs] = Weights[kingDangerThem] = (Weights[kingDangerUs] + Weights[kingDangerThem]) / 2;
|
|
|
|
init_safety();
|
|
}
|
|
|
|
|
|
namespace {
|
|
|
|
// init_eval_info() initializes king bitboards for given color adding
|
|
// pawn attacks. To be done at the beginning of the evaluation.
|
|
|
|
template<Color Us>
|
|
void init_eval_info(const Position& pos, EvalInfo& ei) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
|
|
ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
|
|
|
|
// Init king safety tables only if we are going to use them
|
|
if ( pos.piece_count(Us, QUEEN)
|
|
&& pos.non_pawn_material(Us) >= QueenValueMidgame + RookValueMidgame)
|
|
{
|
|
ei.kingRing[Them] = (b | (Us == WHITE ? b >> 8 : b << 8));
|
|
b &= ei.attackedBy[Us][PAWN];
|
|
ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
|
|
ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
|
|
} else
|
|
ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
|
|
}
|
|
|
|
|
|
// evaluate_outposts() evaluates bishop and knight outposts squares
|
|
|
|
template<PieceType Piece, Color Us>
|
|
Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
assert (Piece == BISHOP || Piece == KNIGHT);
|
|
|
|
// Initial bonus based on square
|
|
Value bonus = OutpostBonus[Piece == BISHOP][relative_square(Us, s)];
|
|
|
|
// Increase bonus if supported by pawn, especially if the opponent has
|
|
// no minor piece which can exchange the outpost piece.
|
|
if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
|
|
{
|
|
if ( !pos.pieces(KNIGHT, Them)
|
|
&& !(same_color_squares(s) & pos.pieces(BISHOP, Them)))
|
|
bonus += bonus + bonus / 2;
|
|
else
|
|
bonus += bonus / 2;
|
|
}
|
|
return make_score(bonus, bonus);
|
|
}
|
|
|
|
|
|
// evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
|
|
|
|
template<PieceType Piece, Color Us, bool Trace>
|
|
Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
|
|
|
|
Bitboard b;
|
|
Square s, ksq;
|
|
int mob;
|
|
File f;
|
|
Score score = SCORE_ZERO;
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
const Square* pl = pos.piece_list(Us, Piece);
|
|
|
|
ei.attackedBy[Us][Piece] = 0;
|
|
|
|
while ((s = *pl++) != SQ_NONE)
|
|
{
|
|
// Find attacked squares, including x-ray attacks for bishops and rooks
|
|
if (Piece == KNIGHT || Piece == QUEEN)
|
|
b = pos.attacks_from<Piece>(s);
|
|
else if (Piece == BISHOP)
|
|
b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
|
|
else if (Piece == ROOK)
|
|
b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
|
|
else
|
|
assert(false);
|
|
|
|
// Update attack info
|
|
ei.attackedBy[Us][Piece] |= b;
|
|
|
|
// King attacks
|
|
if (b & ei.kingRing[Them])
|
|
{
|
|
ei.kingAttackersCount[Us]++;
|
|
ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
|
|
Bitboard bb = (b & ei.attackedBy[Them][KING]);
|
|
if (bb)
|
|
ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
|
|
}
|
|
|
|
// Mobility
|
|
mob = (Piece != QUEEN ? popcount<Max15>(b & mobilityArea)
|
|
: popcount<Full >(b & mobilityArea));
|
|
|
|
mobility += MobilityBonus[Piece][mob];
|
|
|
|
// Decrease score if we are attacked by an enemy pawn. Remaining part
|
|
// of threat evaluation must be done later when we have full attack info.
|
|
if (bit_is_set(ei.attackedBy[Them][PAWN], s))
|
|
score -= ThreatenedByPawnPenalty[Piece];
|
|
|
|
// Bishop and knight outposts squares
|
|
if ( (Piece == BISHOP || Piece == KNIGHT)
|
|
&& !(pos.pieces(PAWN, Them) & attack_span_mask(Us, s)))
|
|
score += evaluate_outposts<Piece, Us>(pos, ei, s);
|
|
|
|
// Queen or rook on 7th rank
|
|
if ( (Piece == ROOK || Piece == QUEEN)
|
|
&& relative_rank(Us, s) == RANK_7
|
|
&& relative_rank(Us, pos.king_square(Them)) == RANK_8)
|
|
{
|
|
score += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
|
|
}
|
|
|
|
// Special extra evaluation for bishops
|
|
if (Piece == BISHOP && pos.is_chess960())
|
|
{
|
|
// An important Chess960 pattern: A cornered bishop blocked by
|
|
// a friendly pawn diagonally in front of it is a very serious
|
|
// problem, especially when that pawn is also blocked.
|
|
if (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1))
|
|
{
|
|
Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
|
|
if (pos.piece_on(s + d) == make_piece(Us, PAWN))
|
|
{
|
|
if (!pos.square_is_empty(s + d + pawn_push(Us)))
|
|
score -= 2*TrappedBishopA1H1Penalty;
|
|
else if (pos.piece_on(s + 2*d) == make_piece(Us, PAWN))
|
|
score -= TrappedBishopA1H1Penalty;
|
|
else
|
|
score -= TrappedBishopA1H1Penalty / 2;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Special extra evaluation for rooks
|
|
if (Piece == ROOK)
|
|
{
|
|
// Open and half-open files
|
|
f = file_of(s);
|
|
if (ei.pi->file_is_half_open(Us, f))
|
|
{
|
|
if (ei.pi->file_is_half_open(Them, f))
|
|
score += RookOpenFileBonus;
|
|
else
|
|
score += RookHalfOpenFileBonus;
|
|
}
|
|
|
|
// Penalize rooks which are trapped inside a king. Penalize more if
|
|
// king has lost right to castle.
|
|
if (mob > 6 || ei.pi->file_is_half_open(Us, f))
|
|
continue;
|
|
|
|
ksq = pos.king_square(Us);
|
|
|
|
if ( file_of(ksq) >= FILE_E
|
|
&& file_of(s) > file_of(ksq)
|
|
&& (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
|
|
{
|
|
// Is there a half-open file between the king and the edge of the board?
|
|
if (!ei.pi->has_open_file_to_right(Us, file_of(ksq)))
|
|
score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
|
|
: (TrappedRookPenalty - mob * 16), 0);
|
|
}
|
|
else if ( file_of(ksq) <= FILE_D
|
|
&& file_of(s) < file_of(ksq)
|
|
&& (relative_rank(Us, ksq) == RANK_1 || rank_of(ksq) == rank_of(s)))
|
|
{
|
|
// Is there a half-open file between the king and the edge of the board?
|
|
if (!ei.pi->has_open_file_to_left(Us, file_of(ksq)))
|
|
score -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
|
|
: (TrappedRookPenalty - mob * 16), 0);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (Trace)
|
|
TracedScores[Us][Piece] = score;
|
|
|
|
return score;
|
|
}
|
|
|
|
|
|
// evaluate_threats<>() assigns bonuses according to the type of attacking piece
|
|
// and the type of attacked one.
|
|
|
|
template<Color Us>
|
|
Score evaluate_threats(const Position& pos, EvalInfo& ei) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
Bitboard b;
|
|
Score score = SCORE_ZERO;
|
|
|
|
// Enemy pieces not defended by a pawn and under our attack
|
|
Bitboard weakEnemies = pos.pieces(Them)
|
|
& ~ei.attackedBy[Them][PAWN]
|
|
& ei.attackedBy[Us][0];
|
|
if (!weakEnemies)
|
|
return SCORE_ZERO;
|
|
|
|
// Add bonus according to type of attacked enemy piece and to the
|
|
// type of attacking piece, from knights to queens. Kings are not
|
|
// considered because are already handled in king evaluation.
|
|
for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
|
|
{
|
|
b = ei.attackedBy[Us][pt1] & weakEnemies;
|
|
if (b)
|
|
for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
|
|
if (b & pos.pieces(pt2))
|
|
score += ThreatBonus[pt1][pt2];
|
|
}
|
|
return score;
|
|
}
|
|
|
|
|
|
// evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
|
|
// pieces of a given color.
|
|
|
|
template<Color Us, bool Trace>
|
|
Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
Score score = mobility = SCORE_ZERO;
|
|
|
|
// Do not include in mobility squares protected by enemy pawns or occupied by our pieces
|
|
const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces(Us));
|
|
|
|
score += evaluate_pieces<KNIGHT, Us, Trace>(pos, ei, mobility, mobilityArea);
|
|
score += evaluate_pieces<BISHOP, Us, Trace>(pos, ei, mobility, mobilityArea);
|
|
score += evaluate_pieces<ROOK, Us, Trace>(pos, ei, mobility, mobilityArea);
|
|
score += evaluate_pieces<QUEEN, Us, Trace>(pos, ei, mobility, mobilityArea);
|
|
|
|
// Sum up all attacked squares
|
|
ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
|
|
| ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
|
|
| ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
|
|
return score;
|
|
}
|
|
|
|
|
|
// evaluate_king<>() assigns bonuses and penalties to a king of a given color
|
|
|
|
template<Color Us, bool Trace>
|
|
Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
Bitboard undefended, b, b1, b2, safe;
|
|
int attackUnits;
|
|
const Square ksq = pos.king_square(Us);
|
|
|
|
// King shelter
|
|
Score score = ei.pi->king_shelter<Us>(pos, ksq);
|
|
|
|
// King safety. This is quite complicated, and is almost certainly far
|
|
// from optimally tuned.
|
|
if ( ei.kingAttackersCount[Them] >= 2
|
|
&& ei.kingAdjacentZoneAttacksCount[Them])
|
|
{
|
|
// Find the attacked squares around the king which has no defenders
|
|
// apart from the king itself
|
|
undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
|
|
undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
|
|
| ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
|
|
| ei.attackedBy[Us][QUEEN]);
|
|
|
|
// Initialize the 'attackUnits' variable, which is used later on as an
|
|
// index to the KingDangerTable[] array. The initial value is based on
|
|
// the number and types of the enemy's attacking pieces, the number of
|
|
// attacked and undefended squares around our king, the square of the
|
|
// king, and the quality of the pawn shelter.
|
|
attackUnits = std::min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
|
|
+ 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
|
|
+ InitKingDanger[relative_square(Us, ksq)]
|
|
- mg_value(ei.pi->king_shelter<Us>(pos, ksq)) / 32;
|
|
|
|
// Analyse enemy's safe queen contact checks. First find undefended
|
|
// squares around the king attacked by enemy queen...
|
|
b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
|
|
if (b)
|
|
{
|
|
// ...then remove squares not supported by another enemy piece
|
|
b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
|
|
| ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
|
|
if (b)
|
|
attackUnits += QueenContactCheckBonus
|
|
* popcount<Max15>(b)
|
|
* (Them == pos.side_to_move() ? 2 : 1);
|
|
}
|
|
|
|
// Analyse enemy's safe rook contact checks. First find undefended
|
|
// squares around the king attacked by enemy rooks...
|
|
b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
|
|
|
|
// Consider only squares where the enemy rook gives check
|
|
b &= PseudoAttacks[ROOK][ksq];
|
|
|
|
if (b)
|
|
{
|
|
// ...then remove squares not supported by another enemy piece
|
|
b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
|
|
| ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
|
|
if (b)
|
|
attackUnits += RookContactCheckBonus
|
|
* popcount<Max15>(b)
|
|
* (Them == pos.side_to_move() ? 2 : 1);
|
|
}
|
|
|
|
// Analyse enemy's safe distance checks for sliders and knights
|
|
safe = ~(pos.pieces(Them) | ei.attackedBy[Us][0]);
|
|
|
|
b1 = pos.attacks_from<ROOK>(ksq) & safe;
|
|
b2 = pos.attacks_from<BISHOP>(ksq) & safe;
|
|
|
|
// Enemy queen safe checks
|
|
b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
|
|
if (b)
|
|
attackUnits += QueenCheckBonus * popcount<Max15>(b);
|
|
|
|
// Enemy rooks safe checks
|
|
b = b1 & ei.attackedBy[Them][ROOK];
|
|
if (b)
|
|
attackUnits += RookCheckBonus * popcount<Max15>(b);
|
|
|
|
// Enemy bishops safe checks
|
|
b = b2 & ei.attackedBy[Them][BISHOP];
|
|
if (b)
|
|
attackUnits += BishopCheckBonus * popcount<Max15>(b);
|
|
|
|
// Enemy knights safe checks
|
|
b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
|
|
if (b)
|
|
attackUnits += KnightCheckBonus * popcount<Max15>(b);
|
|
|
|
// To index KingDangerTable[] attackUnits must be in [0, 99] range
|
|
attackUnits = std::min(99, std::max(0, attackUnits));
|
|
|
|
// Finally, extract the king danger score from the KingDangerTable[]
|
|
// array and subtract the score from evaluation. Set also margins[]
|
|
// value that will be used for pruning because this value can sometimes
|
|
// be very big, and so capturing a single attacking piece can therefore
|
|
// result in a score change far bigger than the value of the captured piece.
|
|
score -= KingDangerTable[Us][attackUnits];
|
|
margins[Us] += mg_value(KingDangerTable[Us][attackUnits]);
|
|
}
|
|
|
|
if (Trace)
|
|
TracedScores[Us][KING] = score;
|
|
|
|
return score;
|
|
}
|
|
|
|
|
|
// evaluate_passed_pawns<>() evaluates the passed pawns of the given color
|
|
|
|
template<Color Us>
|
|
Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
|
|
Score score = SCORE_ZERO;
|
|
|
|
b = ei.pi->passed_pawns(Us);
|
|
|
|
if (!b)
|
|
return SCORE_ZERO;
|
|
|
|
do {
|
|
Square s = pop_1st_bit(&b);
|
|
|
|
assert(pos.pawn_is_passed(Us, s));
|
|
|
|
int r = int(relative_rank(Us, s) - RANK_2);
|
|
int rr = r * (r - 1);
|
|
|
|
// Base bonus based on rank
|
|
Value mbonus = Value(20 * rr);
|
|
Value ebonus = Value(10 * (rr + r + 1));
|
|
|
|
if (rr)
|
|
{
|
|
Square blockSq = s + pawn_push(Us);
|
|
|
|
// Adjust bonus based on kings proximity
|
|
ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr);
|
|
ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 2 * rr);
|
|
|
|
// If blockSq is not the queening square then consider also a second push
|
|
if (rank_of(blockSq) != (Us == WHITE ? RANK_8 : RANK_1))
|
|
ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
|
|
|
|
// If the pawn is free to advance, increase bonus
|
|
if (pos.square_is_empty(blockSq))
|
|
{
|
|
squaresToQueen = squares_in_front_of(Us, s);
|
|
defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
|
|
|
|
// If there is an enemy rook or queen attacking the pawn from behind,
|
|
// add all X-ray attacks by the rook or queen. Otherwise consider only
|
|
// the squares in the pawn's path attacked or occupied by the enemy.
|
|
if ( (squares_in_front_of(Them, s) & pos.pieces(ROOK, QUEEN, Them))
|
|
&& (squares_in_front_of(Them, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<ROOK>(s)))
|
|
unsafeSquares = squaresToQueen;
|
|
else
|
|
unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces(Them));
|
|
|
|
// If there aren't enemy attacks or pieces along the path to queen give
|
|
// huge bonus. Even bigger if we protect the pawn's path.
|
|
if (!unsafeSquares)
|
|
ebonus += Value(rr * (squaresToQueen == defendedSquares ? 17 : 15));
|
|
else
|
|
// OK, there are enemy attacks or pieces (but not pawns). Are those
|
|
// squares which are attacked by the enemy also attacked by us ?
|
|
// If yes, big bonus (but smaller than when there are no enemy attacks),
|
|
// if no, somewhat smaller bonus.
|
|
ebonus += Value(rr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
|
|
}
|
|
} // rr != 0
|
|
|
|
// Increase the bonus if the passed pawn is supported by a friendly pawn
|
|
// on the same rank and a bit smaller if it's on the previous rank.
|
|
supportingPawns = pos.pieces(PAWN, Us) & neighboring_files_bb(file_of(s));
|
|
if (supportingPawns & rank_bb(s))
|
|
ebonus += Value(r * 20);
|
|
|
|
else if (supportingPawns & rank_bb(s - pawn_push(Us)))
|
|
ebonus += Value(r * 12);
|
|
|
|
// Rook pawns are a special case: They are sometimes worse, and
|
|
// sometimes better than other passed pawns. It is difficult to find
|
|
// good rules for determining whether they are good or bad. For now,
|
|
// we try the following: Increase the value for rook pawns if the
|
|
// other side has no pieces apart from a knight, and decrease the
|
|
// value if the other side has a rook or queen.
|
|
if (file_of(s) == FILE_A || file_of(s) == FILE_H)
|
|
{
|
|
if (pos.non_pawn_material(Them) <= KnightValueMidgame)
|
|
ebonus += ebonus / 4;
|
|
else if (pos.pieces(ROOK, QUEEN, Them))
|
|
ebonus -= ebonus / 4;
|
|
}
|
|
score += make_score(mbonus, ebonus);
|
|
|
|
} while (b);
|
|
|
|
// Add the scores to the middle game and endgame eval
|
|
return apply_weight(score, Weights[PassedPawns]);
|
|
}
|
|
|
|
|
|
// evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides, this is quite
|
|
// conservative and returns a winning score only when we are very sure that the pawn is winning.
|
|
|
|
Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) {
|
|
|
|
Bitboard b, b2, blockers, supporters, queeningPath, candidates;
|
|
Square s, blockSq, queeningSquare;
|
|
Color c, winnerSide, loserSide;
|
|
bool pathDefended, opposed;
|
|
int pliesToGo, movesToGo, oppMovesToGo, sacptg, blockersCount, minKingDist, kingptg, d;
|
|
int pliesToQueen[] = { 256, 256 };
|
|
|
|
// Step 1. Hunt for unstoppable passed pawns. If we find at least one,
|
|
// record how many plies are required for promotion.
|
|
for (c = WHITE; c <= BLACK; c++)
|
|
{
|
|
// Skip if other side has non-pawn pieces
|
|
if (pos.non_pawn_material(~c))
|
|
continue;
|
|
|
|
b = ei.pi->passed_pawns(c);
|
|
|
|
while (b)
|
|
{
|
|
s = pop_1st_bit(&b);
|
|
queeningSquare = relative_square(c, make_square(file_of(s), RANK_8));
|
|
queeningPath = squares_in_front_of(c, s);
|
|
|
|
// Compute plies to queening and check direct advancement
|
|
movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
|
|
oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
|
|
pathDefended = ((ei.attackedBy[c][0] & queeningPath) == queeningPath);
|
|
|
|
if (movesToGo >= oppMovesToGo && !pathDefended)
|
|
continue;
|
|
|
|
// Opponent king cannot block because path is defended and position
|
|
// is not in check. So only friendly pieces can be blockers.
|
|
assert(!pos.in_check());
|
|
assert((queeningPath & pos.occupied_squares()) == (queeningPath & pos.pieces(c)));
|
|
|
|
// Add moves needed to free the path from friendly pieces and retest condition
|
|
movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
|
|
|
|
if (movesToGo >= oppMovesToGo && !pathDefended)
|
|
continue;
|
|
|
|
pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
|
|
pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
|
|
}
|
|
}
|
|
|
|
// Step 2. If either side cannot promote at least three plies before the other side then situation
|
|
// becomes too complex and we give up. Otherwise we determine the possibly "winning side"
|
|
if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3)
|
|
return SCORE_ZERO;
|
|
|
|
winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
|
|
loserSide = ~winnerSide;
|
|
|
|
// Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
|
|
b = candidates = pos.pieces(PAWN, loserSide);
|
|
|
|
while (b)
|
|
{
|
|
s = pop_1st_bit(&b);
|
|
|
|
// Compute plies from queening
|
|
queeningSquare = relative_square(loserSide, make_square(file_of(s), RANK_8));
|
|
movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
|
|
pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
|
|
|
|
// Check if (without even considering any obstacles) we're too far away or doubled
|
|
if ( pliesToQueen[winnerSide] + 3 <= pliesToGo
|
|
|| (squares_in_front_of(loserSide, s) & pos.pieces(PAWN, loserSide)))
|
|
clear_bit(&candidates, s);
|
|
}
|
|
|
|
// If any candidate is already a passed pawn it _may_ promote in time. We give up.
|
|
if (candidates & ei.pi->passed_pawns(loserSide))
|
|
return SCORE_ZERO;
|
|
|
|
// Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
|
|
b = candidates;
|
|
|
|
while (b)
|
|
{
|
|
s = pop_1st_bit(&b);
|
|
sacptg = blockersCount = 0;
|
|
minKingDist = kingptg = 256;
|
|
|
|
// Compute plies from queening
|
|
queeningSquare = relative_square(loserSide, make_square(file_of(s), RANK_8));
|
|
movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
|
|
pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
|
|
|
|
// Generate list of blocking pawns and supporters
|
|
supporters = neighboring_files_bb(file_of(s)) & candidates;
|
|
opposed = squares_in_front_of(loserSide, s) & pos.pieces(PAWN, winnerSide);
|
|
blockers = passed_pawn_mask(loserSide, s) & pos.pieces(PAWN, winnerSide);
|
|
|
|
assert(blockers);
|
|
|
|
// How many plies does it take to remove all the blocking pawns?
|
|
while (blockers)
|
|
{
|
|
blockSq = pop_1st_bit(&blockers);
|
|
movesToGo = 256;
|
|
|
|
// Check pawns that can give support to overcome obstacle, for instance
|
|
// black pawns: a4, b4 white: b2 then pawn in b4 is giving support.
|
|
if (!opposed)
|
|
{
|
|
b2 = supporters & in_front_bb(winnerSide, blockSq + pawn_push(winnerSide));
|
|
|
|
while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
|
|
{
|
|
d = square_distance(blockSq, pop_1st_bit(&b2)) - 2;
|
|
movesToGo = std::min(movesToGo, d);
|
|
}
|
|
}
|
|
|
|
// Check pawns that can be sacrificed against the blocking pawn
|
|
b2 = attack_span_mask(winnerSide, blockSq) & candidates & ~(1ULL << s);
|
|
|
|
while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
|
|
{
|
|
d = square_distance(blockSq, pop_1st_bit(&b2)) - 2;
|
|
movesToGo = std::min(movesToGo, d);
|
|
}
|
|
|
|
// If obstacle can be destroyed with an immediate pawn exchange / sacrifice,
|
|
// it's not a real obstacle and we have nothing to add to pliesToGo.
|
|
if (movesToGo <= 0)
|
|
continue;
|
|
|
|
// Plies needed to sacrifice against all the blocking pawns
|
|
sacptg += movesToGo * 2;
|
|
blockersCount++;
|
|
|
|
// Plies needed for the king to capture all the blocking pawns
|
|
d = square_distance(pos.king_square(loserSide), blockSq);
|
|
minKingDist = std::min(minKingDist, d);
|
|
kingptg = (minKingDist + blockersCount) * 2;
|
|
}
|
|
|
|
// Check if pawn sacrifice plan _may_ save the day
|
|
if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
|
|
return SCORE_ZERO;
|
|
|
|
// Check if king capture plan _may_ save the day (contains some false positives)
|
|
if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
|
|
return SCORE_ZERO;
|
|
}
|
|
|
|
// Winning pawn is unstoppable and will promote as first, return big score
|
|
Score score = make_score(0, (Value) 0x500 - 0x20 * pliesToQueen[winnerSide]);
|
|
return winnerSide == WHITE ? score : -score;
|
|
}
|
|
|
|
|
|
// evaluate_space() computes the space evaluation for a given side. The
|
|
// space evaluation is a simple bonus based on the number of safe squares
|
|
// available for minor pieces on the central four files on ranks 2--4. Safe
|
|
// squares one, two or three squares behind a friendly pawn are counted
|
|
// twice. Finally, the space bonus is scaled by a weight taken from the
|
|
// material hash table. The aim is to improve play on game opening.
|
|
template<Color Us>
|
|
int evaluate_space(const Position& pos, EvalInfo& ei) {
|
|
|
|
const Color Them = (Us == WHITE ? BLACK : WHITE);
|
|
|
|
// Find the safe squares for our pieces inside the area defined by
|
|
// SpaceMask[]. A square is unsafe if it is attacked by an enemy
|
|
// pawn, or if it is undefended and attacked by an enemy piece.
|
|
Bitboard safe = SpaceMask[Us]
|
|
& ~pos.pieces(PAWN, Us)
|
|
& ~ei.attackedBy[Them][PAWN]
|
|
& (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
|
|
|
|
// Find all squares which are at most three squares behind some friendly pawn
|
|
Bitboard behind = pos.pieces(PAWN, Us);
|
|
behind |= (Us == WHITE ? behind >> 8 : behind << 8);
|
|
behind |= (Us == WHITE ? behind >> 16 : behind << 16);
|
|
|
|
return popcount<Max15>(safe) + popcount<Max15>(behind & safe);
|
|
}
|
|
|
|
|
|
// apply_weight() applies an evaluation weight to a value trying to prevent overflow
|
|
|
|
inline Score apply_weight(Score v, Score w) {
|
|
return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
|
|
(int(eg_value(v)) * eg_value(w)) / 0x100);
|
|
}
|
|
|
|
|
|
// scale_by_game_phase() interpolates between a middle game and an endgame score,
|
|
// based on game phase. It also scales the return value by a ScaleFactor array.
|
|
|
|
Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf) {
|
|
|
|
assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
|
|
assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
|
|
assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
|
|
|
|
int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
|
|
int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
|
|
return Value((result + GrainSize / 2) & ~(GrainSize - 1));
|
|
}
|
|
|
|
|
|
// weight_option() computes the value of an evaluation weight, by combining
|
|
// two UCI-configurable weights (midgame and endgame) with an internal weight.
|
|
|
|
Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
|
|
|
|
// Scale option value from 100 to 256
|
|
int mg = Options[mgOpt] * 256 / 100;
|
|
int eg = Options[egOpt] * 256 / 100;
|
|
|
|
return apply_weight(make_score(mg, eg), internalWeight);
|
|
}
|
|
|
|
|
|
// init_safety() initizes the king safety evaluation, based on UCI
|
|
// parameters. It is called from read_weights().
|
|
|
|
void init_safety() {
|
|
|
|
const Value MaxSlope = Value(30);
|
|
const Value Peak = Value(1280);
|
|
Value t[100];
|
|
|
|
// First setup the base table
|
|
for (int i = 0; i < 100; i++)
|
|
{
|
|
t[i] = Value(int(0.4 * i * i));
|
|
|
|
if (i > 0)
|
|
t[i] = std::min(t[i], t[i - 1] + MaxSlope);
|
|
|
|
t[i] = std::min(t[i], Peak);
|
|
}
|
|
|
|
// Then apply the weights and get the final KingDangerTable[] array
|
|
for (Color c = WHITE; c <= BLACK; c++)
|
|
for (int i = 0; i < 100; i++)
|
|
KingDangerTable[c][i] = apply_weight(make_score(t[i], 0), Weights[KingDangerUs + c]);
|
|
}
|
|
|
|
|
|
// A couple of little helpers used by tracing code, to_cp() converts a value to
|
|
// a double in centipawns scale, trace_add() stores white and black scores.
|
|
|
|
double to_cp(Value v) { return double(v) / double(PawnValueMidgame); }
|
|
|
|
void trace_add(int idx, Score wScore, Score bScore) {
|
|
|
|
TracedScores[WHITE][idx] = wScore;
|
|
TracedScores[BLACK][idx] = bScore;
|
|
}
|
|
|
|
// trace_row() is an helper function used by tracing code to register the
|
|
// values of a single evaluation term.
|
|
|
|
void trace_row(const char *name, int idx) {
|
|
|
|
Score wScore = TracedScores[WHITE][idx];
|
|
Score bScore = TracedScores[BLACK][idx];
|
|
|
|
switch (idx) {
|
|
case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
|
|
TraceStream << std::setw(20) << name << " | --- --- | --- --- | "
|
|
<< std::setw(6) << to_cp(mg_value(wScore)) << " "
|
|
<< std::setw(6) << to_cp(eg_value(wScore)) << " \n";
|
|
break;
|
|
default:
|
|
TraceStream << std::setw(20) << name << " | " << std::noshowpos
|
|
<< std::setw(5) << to_cp(mg_value(wScore)) << " "
|
|
<< std::setw(5) << to_cp(eg_value(wScore)) << " | "
|
|
<< std::setw(5) << to_cp(mg_value(bScore)) << " "
|
|
<< std::setw(5) << to_cp(eg_value(bScore)) << " | "
|
|
<< std::showpos
|
|
<< std::setw(6) << to_cp(mg_value(wScore - bScore)) << " "
|
|
<< std::setw(6) << to_cp(eg_value(wScore - bScore)) << " \n";
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/// trace_evaluate() is like evaluate() but instead of a value returns a string
|
|
/// suitable to be print on stdout with the detailed descriptions and values of
|
|
/// each evaluation term. Used mainly for debugging.
|
|
|
|
std::string trace_evaluate(const Position& pos) {
|
|
|
|
Value margin;
|
|
std::string totals;
|
|
|
|
TraceStream.str("");
|
|
TraceStream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
|
|
memset(TracedScores, 0, 2 * 16 * sizeof(Score));
|
|
|
|
do_evaluate<true>(pos, margin);
|
|
|
|
totals = TraceStream.str();
|
|
TraceStream.str("");
|
|
|
|
TraceStream << std::setw(21) << "Eval term " << "| White | Black | Total \n"
|
|
<< " | MG EG | MG EG | MG EG \n"
|
|
<< "---------------------+-------------+-------------+---------------\n";
|
|
|
|
trace_row("Material, PST, Tempo", PST);
|
|
trace_row("Material imbalance", IMBALANCE);
|
|
trace_row("Pawns", PAWN);
|
|
trace_row("Knights", KNIGHT);
|
|
trace_row("Bishops", BISHOP);
|
|
trace_row("Rooks", ROOK);
|
|
trace_row("Queens", QUEEN);
|
|
trace_row("Mobility", MOBILITY);
|
|
trace_row("King safety", KING);
|
|
trace_row("Threats", THREAT);
|
|
trace_row("Passed pawns", PASSED);
|
|
trace_row("Unstoppable pawns", UNSTOPPABLE);
|
|
trace_row("Space", SPACE);
|
|
|
|
TraceStream << "---------------------+-------------+-------------+---------------\n";
|
|
trace_row("Total", TOTAL);
|
|
TraceStream << totals;
|
|
|
|
return TraceStream.str();
|
|
}
|